nvent SPECTRACOOL NHZ36 Series User manual

© 2022 nVent 89215759
Rev. A P/N 89215759
SPECTRACOOL
Air Conditioner, HAzArdous LoCAtions
nHz36 ModeL
INSTRUCTION MANUAL

© 2022 nVent 89215759
- 2 -
WARRANTY AND RETURN POLICY
https://hoffman.nvent.com/en/hoffman/warranty-information
TABLE OF CONTENTS
WARRANTY AND RETURN POLICY....................................................................................................................................................................... 2
General Safety Information.................................................................................................................................................................................... 3
Receiving the Air Conditioner ................................................................................................................................................................................ 3
Handling and Testing the Air Conditioner ............................................................................................................................................................ 4
How to Read Model Numbers ............................................................................................................................................................................... 4
Technical Information ............................................................................................................................................................................................ 4
General ........................................................................................................................................................................................................................................ 4
Sequence of Operation.............................................................................................................................................................................................................. 4
Cooling ............................................................................................................................................................................................................................... 4
Standard and Optional Component Operation........................................................................................................................................................................ 5
SMART CONTROLLER....................................................................................................................................................................................................... 5
For cooling (75-100 F range)............................................................................................................................................................................................ 5
Remote Access Control (optional) .................................................................................................................................................................................. 5
Head Pressure Control (optional).................................................................................................................................................................................... 5
115V/230V to 10V Transformer (optional)..................................................................................................................................................................... 5
Door Switch ................................................................................................................................................................................................................................ 5
Active Condensate Management ............................................................................................................................................................................................. 5
When Used With Purge and Pressurized Enclosures.............................................................................................................................................................. 5
Schematics and Wiring Diagrams ............................................................................................................................................................................................ 6
Generic 1 PHASE Schematic (actual unit options may vary)........................................................................................................................................ 6
NHZ36 8K BTU 230V Only Schematic (Actual Unit Options May Vary) ....................................................................................................................... 6
Generic 3 PHASE Schematic (actual unit options may vary)........................................................................................................................................ 7
Generic 1 Phase Wire Diagram (actual unit options may vary)..................................................................................................................................... 8
NHZ36 8K BTU 230V Only Wire Diagram (actual unit options may vary) .................................................................................................................... 9
Generic 3 PHASE Wire Diagram (actual unit options may vary)................................................................................................................................. 10
Dimensional Drawing ........................................................................................................................................................................................... 11
General Safety Information.................................................................................................................................................................................. 12
Installation Instructions ....................................................................................................................................................................................... 12
DIGITAL THERMOSTAT CONTROLLER (OPTIONAL)......................................................................................................................................... 14
Overview.................................................................................................................................................................................................................................... 14
ENERGIZING THE CONTROLLER............................................................................................................................................................................................ 14
CONTROL STATUS INDICATION............................................................................................................................................................................................. 14
DISPLAYING AND CHANGING PROGRAM Settings.............................................................................................................................................................. 17
To view or access the settings....................................................................................................................................................................................... 17
Heat/Cool Operating Parameters ........................................................................................................................................................................................... 17
Alarm Parameters.................................................................................................................................................................................................................... 17
DISPLAYING TEMPERATURE DATA ON SCREEN.................................................................................................................................................................. 19
COMPRESSOR RESTART TIME DELAY................................................................................................................................................................................... 19
ALARM OUTPUT CONTACT .................................................................................................................................................................................................... 19
ALARM INPUT CONNECTION ................................................................................................................................................................................................. 19
PRIMARY-SECONDARY (PS) MODE ....................................................................................................................................................................................... 20
Connecting units together in Primary/Secondary mode...................................................................................................................................................... 20
Connecting units together in Lead/Lag mode....................................................................................................................................................................... 21
AIR CONDITIONER UNIT REMOTE COMMUNICATION FEATURES...................................................................................................................................... 22
USB COMMUNICATION .................................................................................................................................................................................................. 22
ETHERNET COMMUNICATION ...................................................................................................................................................................................... 22
USING HOFFMAN PC INTERFACE TOOL ............................................................................................................................................................................... 23
USB COMMUNICATION MODE ...................................................................................................................................................................................... 23
USB COMMUNICATION MODE ...................................................................................................................................................................................... 24
ETHERNET COMMUNICATION MODE .......................................................................................................................................................................... 25
REMOTE ACCESS CONTROL PIN-OUT................................................................................................................................................................................... 26
General Safety Information.................................................................................................................................................................................. 27
Maintenance ......................................................................................................................................................................................................... 28
Compressor .............................................................................................................................................................................................................................. 28
Inlet Air Filter............................................................................................................................................................................................................................. 28
How To Remove, Clean or Install a New Inlet Air Filter......................................................................................................................................................... 28
Condensate Management and Drain Trap Maintenance...................................................................................................................................................... 28
Condenser and Evaporator Air Movers .................................................................................................................................................................................. 29
Refrigerant Loss....................................................................................................................................................................................................................... 29
Refrigerant Properties Chart (R134a)..................................................................................................................................................................................... 29
6000 BTU/Hr. Unit Characteristics ......................................................................................................................................................................................... 30
8000 BTU/Hr. Unit Characteristics ......................................................................................................................................................................................... 31
Functional Data ........................................................................................................................................................................................................................ 32
F-Gas Information................................................................................................................................................................................................. 32
Service Data .......................................................................................................................................................................................................... 33
6000 BTU/Hr. Components List.............................................................................................................................................................................................. 33
8000 BTU/HR. Components List ............................................................................................................................................................................................ 34
Trouble Shooting .................................................................................................................................................................................................. 36
Basic Air Conditioning Trouble Shooting Check List - SMART CONTROLLER.................................................................................................................... 36
Symptoms and Possible Causes - Remote Access Control Version................................................................................................................................... 37

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GENERAL SAFETY INFORMATION
Please observe the following general safety instructions when assembling and operating the unit:
• Assembling, installing and servicing must only be performed by properly trained specialists.
• When transporting the enclosure with the cooling unit externally mounted, always use an additional shipping brace
to support the cooling unit.
• Do not attempt to operate the air conditioner while it is horizontal or on its side, back or front.
• Operation of air conditioner in areas containing airborne caustics or chemicals can rapidly degrade sealing
properties of materials, deteriorate lters, refrigeration coils, blowers and motors. Contact nVent Equipment
Protection for special recommendations. See Maintenance on page 28.
DANGER
Danger: explosion hazard - do not energize, disconnect, or troubleshoot equipment
unless power has been switched off or the area is known to be non-hazardous.
Unit to be installed and maintained by properly trained personnel only.
Danger : Risque d’explosion – Ne pas alimenter, déconnecter ni dépanner
l’équipement si l’alimentation n’a pas été coupée ou si la zone n’est pas reconnue
comme non dangereuse.
RECEIVING THE AIR CONDITIONER
Inspect the air conditioner. Check for concealed damage that may have occurred during shipment. Look for dents,
scratches, loose assemblies, evidence of oil, etc. Damage evident upon receipt should be noted on the freight bill.
Damage should be brought to the attention of the delivering carrier -- NOT to nVent Equipment Protection -- within
15 days of delivery. Save the carton and packing material and request an inspection. Then le a claim with the
delivering carrier.
nVent Equipment Protection cannot accept responsibility for freight damages; however, we will assist you in any
way possible.
CAUTION
This air conditioner is suitable for use in Class 1, Division 2, Groups A, B, C, D T4A hazardous locations,
or non-hazardous locations only. It is meant to be installed in an enclosure such that the eld wiring and
controls are only accessible with the use of a tool.
Do not attempt to operate the air conditioner while it is horizontal or on its side, back or front. The
refrigeration compressor is lled with lubricating oil. This will cause permanent damage to the air
conditioner and also voids the warranty.
Ce climatiseur peut être utilisé dans des zones dangereuses de Classe 1, Division 2, Groupes A, B, C, D T4A
ou des zones non dangereuses uniquement. L’installation doit être effectuée dans une armoire de telle
sorte que le câblage et les commandes sur le terrain ne soient accessibles qu’à l’aide d’un outil.
Ne pas essayer de faire fonctionner le climatiseur en position horizontale, ou posé sur le côté, l’arrière ou
l’avant. Le compresseur de réfrigération est rempli d’huile lubriante. Cela endommagerait le climatiseur de
manière permanente et annulerait la garantie.
MISE EN GARDE

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HANDLING AND TESTING THE AIR CONDITIONER
If the air conditioner has been in a horizontal position, be certain it is placed in an upright, vertical or mounting
position for a minimum of ve (5) minutes before operating.
TEST FOR FUNCTIONALITY BEFORE MOUNTING THE AIR CONDITIONER TO THE ENCLOSURE.
Refer to the nameplate for proper electrical current requirements, and then wire the unit to a properly grounded
power supply using copper conductors only. Power supply wiring should be restrained after eld installation to
ensure no contact with internal fan. Minimum circuit ampacity should be at least 125% of the amperage shown
on the unit nameplate. No other equipment should be connected to this circuit to prevent overloading
Immediately after applying power, the evaporator blower (enclosure air) should start running. Operate the
air conditioner with the compressor running for ve (5) to ten (10) minutes. You will need to set the cooling
thermostat or controller setpoint below the ambient temperature to operate the compressor.
Condenser air temperatures should be warmer than normal room temperatures within a few minutes after the
condenser impellers start.
See Sequence of Operation on page 4 for specics on how the unit operates when powered up.
HOW TO READ MODEL NUMBERS
NHZ36 04 2 6 G300
12345
1. Identies the type/family of air conditioner and the approximate height (i.e. NHZ36 = Narrow
Hazardous Location family about 36 inches high).
2. This is the air conditioner’s listed capacity in BTU/Hr. at rated conditions. (i.e. 06=6,000 BTU/Hr. at
131/131 F)
3. 1 = 115 Volt, 2 = 230 Volt, 4 = 460 Volt.
4. 6 = 50/60 Hz or 60 Hz only.
5. Unique set of numbers for each air conditioner which identies the accessories on a model.
TECHNICAL INFORMATION
GENERAL
Sensor 2 monitors the enclosure return air temperature to prevent ice buildup on the evaporator coil. If the air
temperature drops below -1 C, the compressor and condenser air mover(s) shut off. They turn back on when the
temperature rises above 15 C.
The compressor and the air movers are equipped with overload protection to guard against excess current and
temperatures.
SEQUENCE OF OPERATION
The air conditioner comes standard with smart controller. During cooling modes, the evaporator fan will be
running.
COOLING
When the enclosure temperature is above the cooling set-point plus the cooling differential, the smart
controller will call for cooling. The compressor is then energized through a solid state relay or contactor.
The condenser impellers will start immediately if the unit is not equipped with an optional head pressure
control switch. If the unit is equipped with an optional head pressure control switch, the condenser
impellers will start once the refrigerant pressure reaches the pressure setting of the switch. Component
specic information is listed below.
Operating the air conditioner below the minimum ambient temperature or above the maximum ambient
temperatures indicated on the nameplate voids all warranties. DO NOT adjust cooling set-point to a
temperature lower than 70 F. Doing so can increase the likelihood of frost buildup on the evaporator coil.
The moisture that the enclosure air can contain is limited. If moisture ows from the drain tube
continuously this can only mean that ambient air is entering the enclosure. Be aware that frequent
opening of the enclosure’s door admits humid air that the air conditioner must then dehumidify.

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STANDARD AND OPTIONAL COMPONENT OPERATION
SMART CONTROLLER
The standard NHZ36 air conditioner uses our standard smart controller. The setpoint equals the
temperature that the air conditioner turns off. The controller has a 7 F differential from setpoint until it
calls for cooling. An example of operation is shown below.
FOR COOLING (75-100 F RANGE)
• Thermostat setpoint = 80 F
• Cooling turns on at 87 F
• Cooling turns off at 80 F
REMOTE ACCESS CONTROL (OPTIONAL)
See Remote Access Control (optional) on page 5
HEAD PRESSURE CONTROL (OPTIONAL)
Unit is set at the factory, no adjustment necessary.
At a saturated condenser temperature of 85 F (95 psig), the condenser fans will power off. At a saturated
condenser temperature of 117 F (165 psig), the condenser fans will power on.
115V/230V TO 10V TRANSFORMER (OPTIONAL)
This transformer powers the thermal display.
DOOR SWITCH
Several door switches may be connected in series and operated on one cooling unit. The door switch only
supports a oating connection,no external voltages. Remove jumper from terminals 3 and 4 of the connector and
connect the door switch to the two terminals if a door switch is available.
ACTIVE CONDENSATE MANAGEMENT
At low temperatures and high humidity levels inside the enclosure, condensation may form on the evaporator coil.
The air conditioner will continuously evaporate the water that may be in the drain pan due to condensation from
the evaporator coil into the external air stream. Excess condensate is routed downwards out of the air conditioner
via a tube tting at the bottom of the condenser side of the unit. A 10 mm inside diameter tube can be attached
to the tting and routed to a nearby drain.
WHEN USED WITH PURGE AND PRESSURIZED ENCLOSURES
This air conditioner will operate safely in a Class 1 Division 2 Groups A, B, C and D hazardous location on both
exterior and interior sides. It does not require a purge and pressurized enclosure, but if it is to be installed on one,
the following should be considered.
The active condensate management system functionally described above is possible due to a drain trap directly
connecting and routing condensation from the evaporator coil pan to the ambient side where it collects in the
condensate evaporator pan.
During initial purging of an enclosure or after long periods of operation in a pressurized system utilizing a dry
protective and/or inert gas supply, the drain trap can eventually dry out and allow a small amount of protective
gas to leak outward of the enclosure through the drain trap. A leakage should not immediately be associated with
a hazardous condition. If continuous positive pressure is maintained inside an enclosure, the protective gas will
leak out to ambient and prevent hazardous gasses from entering. A typical enclosure pressurization system can
compensate for this and maintain proper enclosure pressure.
If the pressurization system cannot compensate for the additional leakage, a drain trap seal can be created by
priming the air conditioner drain. This can be done by de-energizing and opening the enclosure for access to the
evaporator coil, and carefully pouring clean water (approx. 1 cup) into the face of the coil. With water present, the
drain trap should be fully primed and sealed. Opening the enclosure can also introduce humidity back into the
enclosure which will eventually condense on the evaporator coil and become part of the seal in the drain trap.

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SCHEMATICS AND WIRING DIAGRAMS
GENERIC 1 PHASE SCHEMATIC (ACTUAL UNIT OPTIONS MAY VARY)
NHZ36 8K BTU 230V ONLY SCHEMATIC (ACTUAL UNIT OPTIONS MAY VARY)

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GENERIC 3 PHASE SCHEMATIC (ACTUAL UNIT OPTIONS MAY VARY)

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GENERIC 1 PHASE WIRE DIAGRAM (ACTUAL UNIT OPTIONS MAY VARY)

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NHZ36 8K BTU 230V ONLY WIRE DIAGRAM (ACTUAL UNIT OPTIONS MAY VARY)

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GENERIC 3 PHASE WIRE DIAGRAM (ACTUAL UNIT OPTIONS MAY VARY)

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DIMENSIONAL DRAWING
WARM
AIR OUT
AMBIENT
AIR IN
CLEANABLE, REUSABLE
ALUMINUM INLET AIR FILTER
PULLS OUT FRONT
ACCESS HOLE TO
.375 [9.5] O.D. DRAIN STUB
.78
19.7
14.00
355.7
9.37
238.1
11.50
292.1
36.01
914.7
22.31
566.7
ENCLOSURE
AIR IN
REMOVABLE
HANGING TABS
COOL
AIR OUT
DOOR SWITCH/
MALFUNCTION ALARM
MATING CONNECTOR
(SHIPPED LOOSE)
.50
12.7
28.80
731.5
16.50
419.1
2X
A
33.50
850.9
2X
8.00
203.2
5.00
127
10.00
254
25.00
635
2X
POWER
INPUT
SMART
CONTROLLER
DOOR SWITCH/
MALFUNCTION ALARM
CONNECTOR
REMOTE ACCESS
CONTROLLER
(OPTIONAL)

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GENERAL SAFETY INFORMATION
Please observe the following general safety instructions when assembling and operating the unit:
• Assembling, installing and servicing must only be performed by properly trained specialists.
• When transporting the enclosure with the cooling unit externally mounted, always use an additional shipping brace
to support the cooling unit.
• Do not attempt to operate the air conditioner while it is horizontal or on its side, back or front.
• Operation of air conditioner in areas containing airborne caustics or chemicals can rapidly degrade sealing
properties of materials, deteriorate lters, refrigeration coils, blowers and motors. Contact nVent Equipment
Protection for special recommendations. See Maintenance on page 28.
DANGER
Danger: explosion hazard - do not energize, disconnect, or troubleshoot equipment
unless power has been switched off or the area is known to be non-hazardous.
Unit to be installed and maintained by properly trained personnel only.
Danger: Risque d’explosion – Ne pas alimenter, déconnecter ni dépanner
l’équipement si l’alimentation n’a pas été coupée ou si la zone n’est pas reconnue
comme non dangereuse.
INSTALLATION INSTRUCTIONS
1. Refer to nameplate for hazardous location rating.
2. Install a suitable switch to de-energize the air conditioner for repairs or remove the fuse.
3. Inspect the air conditioner and verify correct functionality before mounting the air conditioner. See
Handling and Testing the Air Conditioner on page 4.
4. Using the mounting gasket kit provided with the unit, install gaskets to the air conditioner.
5. When considering a location for the unit, it is recommended that a six (6) inch clearance be
maintained on at least one side of the air conditioner. It is also recommended that twenty (20)
inches of clearance be allowed from the front of the unit for cover removal.
6. Figure 1 and the cutout template included with the unit will assist in preparing the enclosure for
installation of the unit. NOTE: Mount the unit within 3° from vertical.
7. Mount air conditioner on enclosure taking care not to damage the mounting gasket. The
mounting gasket is the seal between the air conditioner and the enclosure. Avoid dragging the air
conditioner on the enclosure with the mounting gasket attached as this could cause rips or tears
in the gasket and risk losing the water tight seal.
8. To avoid cross-threading mounting inserts, start bolts by hand before tightening with a wrench or
ratchet driver.
9. Allow unit to remain upright for a minimum of ve (5) minutes before starting. CAUTION! Air
conditioner must be in upright position during operation.
10. Refer to the nameplate for electrical requirements. Wire the unit to a properly grounded power
supply. Electrical circuit should be fused with slow blow or HACR circuit breaker.
11. Adjust the controller to the desired cabinet temperature. Refer to DISPLAYING AND CHANGING
PROGRAM Settings on page 17 for controller adjustments and operation.

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CAUTION
The unit is meant to be installed in an enclosure suitable for the environment listed previously and such that
the eld wiring and controls are only accessible with the use of a tool.
When installed on an enclosure, only the front/face side, ambient air in, and ambient air out can be exposed
to the environment.
L’unité doit être installée dans une armoire adaptée à l’environnement susmentionné et de telle sorte que le
câblage et les commandes sur le terrain ne soient accessibles qu’à l’aide d’un outil.
Lors d’une installation sur une armoire, seule la face avant/latérale, l’entrée d’air ambiant et la sortie d’air
ambiant peuvent être exposées à l’environnement.
MISE EN GARDE
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89074387
Surface Mount
Figure 1
Cut-out Drawing

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DIGITAL THERMOSTAT CONTROLLER (OPTIONAL)
OVERVIEW
The digital thermostat (controller) is a parametric controller for the complete management of air conditioners.
All settings are pre-programmed at the factory. Cooling/heating setpoint, cooling/heating differential and high/
low temperature setpoint are designed to be adjustable by the operator. All alarms are outputted through the
alarm relay. In addition, if Hoffman network card (Remote Access Control (RAC) Module) is used the parameters
that state above and alarms are accessible remotely through Ethernet connection utilizing SNMP, Modbus TCP,
EtherNet/IP, and Pronet protocol . A USB connection from the network card is also provided with accessibility
to the digital thermostat controller utilizing Modbus RTU and RS-845 serial bus. In addition, the USB connection
is also used to read the network information from the Hoffman network card and temperature setpoints and
alarm from the controller. Note that Hoffman network card (RAC module) is acting as a gateway to the digital
thermostat where temperature setpoints and alarm can be viewed and/or changed remotely.
Note: nVent Hoffman network card (RAC module) is an optional accessory, therefore, some of
the air conditioners ship without the network card but it is upgradable upon request.
ENERGIZING THE CONTROLLER
The digital controller is wired and programmed at the factory to operate when power is applied to the air
conditioner. In normal condition, the evap fan starts operating after the completion of the self-evaluation which
is less than 30 seconds and fan icon should be illuminated along with the inlet and outlet temperature data (if an
option outlet temperature sensor is installed).
CONTROL STATUS INDICATION
The display has numerous symbols to indicate the various controller functions such as cooling, heating, alarming,
evaporator fan, and heating. Indicators (icons) are steady illuminated on screen when active.
Figure 2
Display

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KEYPAD
SYMBOL COLOR ICON INDICATION ICON STATUS
Red Alarm - active when alarm is detected Flashing when alarm is detected
White
Keypad Select – access to passcode , hold 5 sec to
turn unit ON/OFF, parameter menu, parameter setting,
write or save to EEPROM, and hold for 3sec to return to
main screen
ON
White Keypad Up – navigate to previous parameter and
increasing parameter variable ON only when reviewing parameters
White Keypad Down – navigate to next parameter and
decreasing parameter variable, all inputs, unit status. ON
MAIN FIELD
SYMBOL COLOR ICON INDICATION ICON STATUS
°C White When operating temperature in degrees Celsius ON
°F White When operating temperature in degrees of Fahrenheit ON
Main Field Line 1 White Display inlet temperature ON
Main Field Line 2 Orange
1. Display outlet temperature in standalone
mode if outlet sensor is present
2. Displays device ID for primary-secondary
mode up to 10 units, 1:10 … 10:10 or lead-
lag mode up to 2 units, 1:2… 2:2
ON
ICONS
SYMBOL COLOR ICON INDICATION ICON STATUS
White Compressor Running
• Flashing while waiting for
compressor to turn ON
• Steady ON while compressor
is running
White Evaporator Running ON
White Electric heater ON ON
White Primary and/or lead controller ON
White Freeze control Compressor and Condenser fan OFF while
illuminated
White Power ON ON

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DISPLAYING AND CHANGING PROGRAM SETTINGS
TO VIEW OR ACCESS THE SETTINGS
TO ACCESS FOLDER MENUS:
1. Press button to display passcode screen, the screen displays PSd on line 1 and 0000 on line 2.
2. Press button to access to passcode , the rst digit of 0000 is ashing and press 3 more times
until the last digit of 0000 ashes.
3. Press arrow two times to change the 0 to 2. Press for access to folder menus.
Note: to exit the security level to the main screen wait one minute with no action or Press
arrow until LOG Out message displays, then press button.
TO CHANGE A PARAMETER SETTING
1. Once in the folder menu navigate to the desired setting to be changed using the arrow to scroll
and button to access a menu or parameter.
2. To change a parameter Press button and parameter value will begin to ash.
3. Press /arrow to the desire value.
4. Press button to save the setting and the screen will revert to the parameter mnemonic.
Note: if button is not pressed, the new setpoint is not saved.
To exit the parameter settings to the main screen wait one minute with no action or Press arrow
few times until ESC displays, then press button to return to UoF screen. From the UoF screen
Press arrow few times until LOG Out message displays, then press button to return to the
main screen.
Selecting ESC returns to folder menu.
Selecting LOG out returns to main screen.
HEAT/COOL OPERATING PARAMETERS
Mnemonic Parameter Description Default Value Range
CSt1Cooling setpoint 80 F 72 F to 120 F
Cd (Cd1)1Cooling differential 7 F 2 F to 25 F
Cd24Cooling differential 2 15 F
HSt2 3 Heating setpoint 50 F 45 F to 60 F
Hd3Heating differential 7 F 2 F to 25 F
1 Compressor or cooling turns ON at CSt + Cd and OFF at CSt
2 Heater or heating turns ON at HSt and OFF at HSt + Hd
3 Heating mode is only applied to a unit with heater option
4 Cooling differential 2 is only applied to 2-stage compressor and lead-lag application
ALARM PARAMETERS
Mnemonic Para Description Default value
Ht High temperature alarm setpoint 125 F
Lt Low temperature alarm setpoint 40 F
dO Door open alarm setting NC
ArOP Alarm relay output NO
NOTES: (4) The alarm relay output logic is designed to be congurable

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VIEW ALARMS
Alarms may be viewed when the alerting icon is ashing.
1. On the main screen, press the alerting icon button
2. The screen displays the most recent or newest alarm where the alarm code display on line 1 and
the alerting icon is now in steady
3. Press arrow to view next alarm if there are more than one
4. Press arrow to display ESC, then press button to return to the main screen
VIEW THE ALARMS IN THE ALARM HISTORY FOLDER
1. Follow instructions above to enter the passcode and open the alarm history folder (AHiF).
2. Press button to access to the alarm history.
3. Press arrow to display the mnemonic alarm on line 1 and time, month, and day display on line
2. For example, low temp alarm (Lt) displays on line 1 and 09:24 and 0706 display on line 2 in
sequence. Note that the time, and date recorded in the alarm history is based on the local real-
time-clock if congured after installation.
4. Press arrow to view next alarm. The controller is able to retain up to 25 events
5. Press arrow until the screen displays ESC, then press button to return to the main screen
or if no action for longer than 60 seconds the screen will be automatically revert to the main
screen.
NOTE: if no alarms are present then only ESC will be displayed in the folder.
There are seven possible alarms (non-latching) detectable by the controller and are indicated on
the controller display. All alarms are accessible locally. If a Hoffman network card (RAC module) is
used, alarms are also accessible remotely through the Ethernet and USB connection.
Mnemonic Alarm Description Cause Result Alarm Relay Output
dO Door open alarm Enclosure door opens or not
properly close Compressor and evap fan turn OFF in duration of alarm Closed
S1F Inlet temperature
sensor fault Inlet temp probe failed No effect on function, controller
continue operating as normal using
outlet sensor with setpoint of 50 F Closed
S2F Outlet temperature
sensor fault Outlet temp probe failed No effect on function but loss freeze protection Closed
LA Malfunction alarm MALF high pressure switch
opens No effect on function Closed
Ht High temp warning Enclosure air exceeds high
temp alarm setpoint No effect on function Closed
Lt Low temp warning Enclosure air drops below
low temp alarm setpoint No effect on function -
FA Frost alarm Evaporator coil freezes
Compressor and condenser fan turns
OFF for the duration of alarm. Alarm
clears when the outlet temperature
sensor reaches 59 F
Closed

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TO RESET THE ALARMS IN ALARM HISTORY FOLDER
The controller is designed with ability to reset or clear the alarm history
1. Follow instructions above to enter the passcode and open the reset folder (rStF).
2. The screen displays rSAL on line 2 and nO on line 1, press button the nO is ashing
3. Press arrow to change nO to YeS, then press button reset the alarms. The screen ashes
once and returns to rSAL with nO one line 2
4. Press arrow to navigate to ESC, then press to returns to rStF screen.
5. Press arrow to navigate to LOG Out, then press button to return to the main screen or if no
action for longer than 60 seconds the screen will be automatically reverted to the main screen.
TO RESET PARAMETERS TO FACTORY DEFAULT
This option is ONLY applied if the operator wants to reset all control parameters back to factory default.
1. Follow instructions above to enter the passcode and open the reset folder (rStF).
2. The screen displays rSAL, press arrow to navigate to rSPA and then press button
3. The screen displays rSPA one line 1 and the word nO on line 2 in steady state, press button and
then the word nO is ashing and ready to change
4. Press arrow to change nO to YES. Press button the screen displays PSd with 0000 on line 2
5. Press button to enter to passcode. Press button few times until the last digit of 0000 ashing
6. Press arrow to change 0 to 2, press button to authorize the reset of the parameters
7. The screen returns to rSPA screen in steady state.
8. Press arrow to navigate to ESC, then press to returns to rStF screen.
9. Press arrow to navigate to LOG Out, then press button to return to the main screen or if no
action for longer than 60 seconds the screen will be automatically reverted to the main screen.
DISPLAYING TEMPERATURE DATA ON SCREEN
There are two temperature probes in the air conditioner where one is reading the enclosure air temperature
incoming to the air conditioner and other is reading the cooled air leaving the air conditioner and entering the
enclosure. Both temperature data are displayed on the screen where line 1 is the reading of the inlet temperature
and line 2 is the reading of the outlet temperature.
COMPRESSOR RESTART TIME DELAY
A factory set 3 minute (180 seconds) restart delay exists to reduce residual back pressure before allowing
the compressor to restart. The compressor will stay off for the entire restart duration after the compressor is
disabled. A ashing compressor icon on the display indicating that the unit is in a compressor restart delay
mode while calling for cooling or waiting for compressor to turn ON.
ALARM OUTPUT CONTACT
The digital controller has a normally open dry contact alarm output with a resistive load rating of 250VAC @ 5
amps max. The two yellow 18 AWG wires located at the back of the air conditioner provide a connection to this
output. Note: do not apply power to this normally open dry contact (two yellow 18 AWG wire). This alarm relay
output is congurable and provides user with the ability to change the conguration to support their external
device. Parameter C21 controls the alarm relay output logic and can be accessed through security code “0022” in
the PArF folder.
Para Description Conguration
C21 Alarm relay output logic 0 = normally open (NO) – factory default
1 = normally closed (NC)
ALARM INPUT CONNECTION
The digital controller can accept a dry contact/switch input via the two 18 AWG white wires located at the back
of the air conditioner. This input is associated with the controller display alarm mnemonic dO (door open). To use
this feature, remove the splice connector, and connect the two white wires to customer supplied enclosure door
switch in its place. Note: do NOT apply power to this dry contact input.

© 2022 nVent 89215759
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PRIMARY-SECONDARY (PS) MODE
Note: during normal operation, in both the primary-secondary (PS) and lead-lag (LL) operating modes,
line 2 displays the device ID, not the outlet temperature. The outlet temperature can be viewed on line
1 by pressing arrow.
Primary-secondary (PS) mode shares the same hardware and source code as standalone mode, but offers more
functionality and features. The controller ships from the factory in Standalone Mode. PS mode is congured
manually in the eld after the installation. This option allows the user to operate the air conditioner in a group
network with up to 10 units. To support PS mode, three parameters, H01, H02, and H03 need to be congured.
H01 species the operating mode, H02 species the device ID, and H03 species the total number of the units in
the group network.
Before conguring to operate in PS mode, the user should understand the functionality of the PS mode.
1. In the PS mode, all units operate off the cooling/heating setpoint and differential of the primary
unit. The system prevents setpoint changes from secondary units.
2. The primary unit monitors the enclosure temperatures of all the units and manages the ON/OFF
status of cooling and heating based on the unit reporting the highest temperature.
3. When cooling is initiated the primary unit energizes rst. Secondary units are energized
sequentially at 10 second intervals. When heating is initiated all units turn on heat together. When
cooling or heating is satised all units turn off together.
4. If the number of units communicating on the network doesn’t match the value in H03 then
the primary unit will display alarm LC, and the secondary units will display alarm LC1 until the
communication re-established.
5. Any unit that loses communication with the primary unit will enter standalone mode and continue
operating based on its own temperature probe until communication is re-established.
6. All temperature setpoints and alarms can be viewed remotely if one of the ACUs is equipped with
Hoffman network card (RAC module).
7. Best recommendation is to congure the ACU that has Hoffman network card to be the primary
one.
CONNECTING UNITS TOGETHER IN PRIMARY/SECONDARY MODE
Primary - Device ID 1 Secondary - Device ID 2 Secondary - Device ID 3 Secondary - Device ID 10
Figure 3
Primary-secondary network connectivity